5 RISK CHARACTERIZATION – HUMAN HEALTH
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Statutory Documents - IMO Publications and Documents - Circulars - Ballast Water Management - BWM.2/Circular.13/Rev.4 – International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004 – (20 July 2017) - Annex – Revised Methodology for Information Gathering and Conduct of Work of the GESAMP-BWWG. Approved by MEPC 71 on 7 July 2017 - 5 RISK CHARACTERIZATION – HUMAN HEALTH

5 RISK CHARACTERIZATION – HUMAN HEALTH

 This section describes the risk characterization on human health specified in paragraphs 5.3.12, 5.3.13 and section 6.3 of Procedure (G9).

5.1 In risk characterization for human health, the procedure is to compare the exposure levels to which the target groups are exposed or likely to be exposed with those levels at which no toxic effects from the chemicals are expected to occur.

5.2 A quantitative risk assessment is an iterative process and normally includes four steps:

  • .1 Hazard identification – what are the substances of concern and what are their effects?

  • .2 Dose (concentration) – response (effect) relation – what is the relationship between the dose and the severity or the frequency of the effect?

  • .3 Exposure assessment – what is the intensity, and the duration or frequency of exposure to an agent?

  • .4 Risk characterization – how to quantify the risk from the above data?

5.3 In assessing an acceptable level of a particular substance, the procedure usually follows moving from animal experiments or preferably human data (e.g. epidemiological studies) giving a No Observed Adverse Effect Level (NOAEL) or a Lowest Observed Adverse Effect Level (LOAEL) to derive an exposure limit above, which humans should not be exposed to (Derived No Effect Level – DNELs). Taking into account the critical health effect that can be exerted by a threshold mode of action, the lowest DNEL for each exposure route should be established by dividing the value of the critical dose descriptor, e.g. N(L)OAEL, by an assessment factor (AF) to allow for extrapolation from experimental data to real human exposure situations. Comparison of this exposure limit with a measured or estimated exposure level is then used to judge whether the situation is satisfactory or whether risk management measures are required.

5.4 Based on the most suitable N(L)OAEL, a DNEL for further risk assessment is derived. Generally, the DNEL is determined by applying an Assessment Factor (AF) according to the formula:

5.5 Two groups of potentially exposed persons are distinguished as follows:

  • .1 workers (crew and port State control officers); and

  • .2 general public.

5.6 Particularly in case of occupational exposure, it is of primary importance to fully understand the processes and unit operations in which exposure occurs, and the actual activities resulting in exposure (potentially exposed individuals, frequency and duration of the routes of concern, what personal protective equipment and control measures are used to reduce or mitigate exposure, and how effective they are).

5.7 It is useful to conduct an assessment using "worst-case" assumptions. If this indicates a risk of no concern, the assessment needs no further refinement.

5.8 Exposure should always be assessed in the first instance for the unprotected worker and, if appropriate, a second assessment, should be made taking personal protective equipment (PPE) into account.

5.9 In the risk characterization, these estimates are combined with the results of the effects assessment and conclusions are drawn whether or not there is a concern for any scenarios assessed (Risk Characterization Ratio (RCR) = Exposure/DNEL).

5.10 When a risk assessment results in the conclusion that there is an unacceptable risk (RCR > 1), a second Tier assessment should be performed by considering specific risk control measures in order to lower this risk to acceptable levels (protective clothing, respirators and self-contained breathing apparatus, crew training, good operational practices, etc.).

5.11 The effect assessment of the Active Substances, Preparations and Relevant Chemicals should include a screening on carcinogenic, mutagenic and endocrine disruptive properties, taking into account available information. There is no requirement for additional testing. If the screening results give rise to concerns, this should give rise to a further assessment.

5.12 As a general rule, exposure in the workplace must be avoided or minimized as far as technically feasible. In addition, a risk for the general public from secondary exposure to a non-threshold carcinogenic substance is also unacceptable.

5.13 Carcinogens can have a threshold or non-threshold mode of action. When it comes to threshold carcinogens, these can be assessed by using a Derived No-Effect Level (DNEL) approach, however in the case of the non-threshold carcinogens a different approach to risk assessment is recommended. In these cases, a Derived Minimal Effect Level (DMEL) should be determined.

5.14 Cancer risk levels between 10-4 to 10-6 are normally seen as indicative tolerable risk levels when setting DMELs. Where these values are available from internationally recognized bodies, they can be used to set DMELs for risk assessment purposes.

5.15 The assessment of the carcinogenicity, mutagenicity and reproductive toxicity properties of the Active Substance and the Relevant Chemicals takes place as part of the PBT assessment (see paragraph 6.1 of this Methodology).

5.16 Forty-one chemicals most commonly associated with treated ballast water (see appendix 6) have been already assessed by the GESAMP-BWWG. The DNEL and DMEL values can be found online in the GESAMP-BWWG Database of chemicals most commonly associated with treated ballast water (https://gisis.imo.org/).

5.17 The human risk assessment approach is described in more detail in appendix 4.

Parent topic: Annex – Revised Methodology for Information Gathering and Conduct of Work of the GESAMP-BWWG. Approved by MEPC 71 on 7 July 2017
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